A variety of furnaces has been used heretofore for the smelting and/or refining of cooper either in the form of so-called raw copper or so-called blister copper.
For example, in addition to electric furnaces and reverberatory furnaces for this purpose, it has been proposed to provide shaft furnaces in association with hearth furnaces.
As has been described in the printed German application (Auslegeschrift) DT-AS 2,062,144, for example, copper can be melted in the shaft furnace and can be transferred through a tap into one or more reverberatory furnaces or tilting furnaces.
The molten copper may also be transferred into furnaces which are connected in series and in which the copper is blown with air to remove the impurities. Then the copper is treated with a poling gas which controls the oxygen content.
The smelting of raw copper or blister copper in the shaft of the furnace has a significant disadvantage in that the lining of the furnace may be subjected to excessive wear because of its contact with the molten slag.
Furthermore, the burners must generally be operated at a pressure substantially in excess of atmospheric pressure while the copper pile in the region of the melting zone has a low and often nonuniform permeability to gas.